Thiamin auxotrophy in yeast through altered cofactor dependence of the enzyme acetohydroxyacid synthase

Byrne, Kerry L.; Meacock, Peter A.

doi:10.1099/00221287-147-9-2389

Cited by 6 publications

(1 citation statement)

References 36 publications

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“…Since studies on the AHAS activity (e.g. Byrne and Meacock 2001; Duong et al 2011; Magee and de Robichon-Szulmajster 1968; Pang and Duggleby 2001) revolve around an assay based on the ability of AHAS to convert pyruvate into α-acetolactate, it would be of interest to measure the activity of the α-ketobutyrate to α-acetohydroxybutyrate reaction as well, and the effect of various amino acids on its activity.…”

Section: Discussionmentioning

confidence: 99%

Influence of valine and other amino acids on total diacetyl and 2,3-pentanedione levels during fermentation of brewer’s wort

Krogerus

Gibson

2013

Appl Microbiol Biotechnol

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Undesirable butter-tasting vicinal diketones are produced as by-products of valine and isoleucine biosynthesis during wort fermentation. One promising method of decreasing diacetyl production is through control of wort valine content since valine is involved in feedback inhibition of enzymes controlling the formation of diacetyl precursors. Here, the influence of valine supplementation, wort amino acid profile and free amino nitrogen content on diacetyl formation during wort fermentation with the lager yeast Saccharomyces pastorianus was investigated. Valine supplementation (100 to 300 mg L−1) resulted in decreased maximum diacetyl concentrations (up to 37 % lower) and diacetyl concentrations at the end of fermentation (up to 33 % lower) in all trials. Composition of the amino acid spectrum of the wort also had an impact on diacetyl and 2,3-pentanedione production during fermentation. No direct correlation between the wort amino acid concentrations and diacetyl production was found, but rather a negative correlation between the uptake rate of valine (and also other branched-chain amino acids) and diacetyl production. Fermentation performance and yeast growth were unaffected by supplementations. Amino acid addition had a minor effect on higher alcohol and ester composition, suggesting that high levels of supplementation could affect the flavour profile of the beer. Modifying amino acid profile of wort, especially with respect to valine and the other branched-chain amino acids, may be an effective way of decreasing the amount of diacetyl formed during fermentation.

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Section: Discussionmentioning

confidence: 99%

Influence of valine and other amino acids on total diacetyl and 2,3-pentanedione levels during fermentation of brewer’s wort

Krogerus

Gibson

2013

Appl Microbiol Biotechnol

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Current Awareness

2002

Yeast

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In order to keep subscribers up‐to‐date with the latest developments in their field, this current awareness service is provided by John Wiley & Sons and contains newly‐published material on yeasts. Each bibliography is divided into 10 sections. 1 Books, Reviews & Symposia; 2 General; 3 Biochemistry; 4 Biotechnology; 5 Cell Biology; 6 Gene Expression; 7 Genetics; 8 Physiology; 9 Medical Mycology; 10 Recombinant DNA Technology. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted. (4 weeks journals ‐ search completed 14th. Nov. 2001)

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Effects of pyruvate dehydrogenase subunits overexpression on the α-ketoglutarate production in Yarrowia lipolytica WSH-Z06

Guo

Madzak

et al. 2014

Appl Microbiol Biotechnol

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Yarrowia lipolytica WSH-Z06 harbours a promising capability to oversynthesize α-ketoglutarate (α-KG). Its wide utilization is hampered by the formation of high concentrations of pyruvate. In this study, a metabolic strategy for the overexpression of the α and β subunits of pyruvate dehydrogenase E1, E2 and E3 components was designed to reduce the accumulation of pyruvate. Elevated expression level of α subunit of E1 component improved the α-KG production and reduced the pyruvate accumulation. Due to a reduction in the acetyl-CoA supply, neither the growth of cells nor the synthesis of α-KG was restrained by the overexpression of β subunit of E1, E2 and E3 components. Furthermore, via the overexpression of these thiamine pyrophosphate (TPP)-binding subunits, the dependency of pyruvate dehydrogenase on thiamine was diminished in strains T1 and T2, in which α and β subunits of E1 component were separately overexpressed. In these two recombinant strains, the accumulation of pyruvate was insensitive to variations in exogenous thiamine. The results suggest that α-KG production can be enhanced by altering the dependence on TPP of pyruvate dehydrogenase and that the competition for the cofactor can be switched to ketoglutarate dehydrogenase via separate overexpression of the TPP-binding subunits of pyruvate dehydrogenase. The results presented here provided new clue to improve α-KG production.

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Thiamin auxotrophy in yeast through altered cofactor dependence of the enzyme acetohydroxyacid synthase

Cited by 6 publications

References 36 publications

Influence of valine and other amino acids on total diacetyl and 2,3-pentanedione levels during fermentation of brewer’s wort

Influence of valine and other amino acids on total diacetyl and 2,3-pentanedione levels during fermentation of brewer’s wort

Current Awareness

Effects of pyruvate dehydrogenase subunits overexpression on the α-ketoglutarate production in Yarrowia lipolytica WSH-Z06

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